1. Field of the invention:
The present invention relates to a paper feed unit for feeding paper on which an image is formed in an image forming apparatus. More particularly, it relates to a paper feed unit having a replaceable roller which rotationally contacts paper so as to feed the paper and a paper detection switch for detecting the presence of the paper to be fed by the roller.
2. Description of the prior art:
In an image forming apparatus, an image is formed on paper fed by a paper feed unit. Generally, a paper feed unit of an image forming apparatus is so constructed that a roller mounted on a paper feed shaft rotates while contacting the paper to be fed for feeding the paper into an image forming section. Because the roller wears due to rotational contact with the paper, the paper feed performance will deteriorate with use over a long period of time. Therefore, the roller is replaceably mounted, as is known. Also, the paper feed unit is usually provided with a paper detection device for detecting the presence of the paper to be fed. Because of the need for detecting the presence of the paper that the roller rotationally contacts, the paper detection device is disposed adjacent to the roller, which in turn presents interference when replacing the roller. In particular, when the paper is transported by making reference to the center of its width orthogonal to its transporting direction, since the paper detection device is so disposed as to detect that center, the paper detection device has to be removed for the time when replacing the roller. However, since the paper detection device is usually fixed in position with a screw, etc., the paper detection device must be refixed in position with the screw, etc., after removing the paper detection device and replacing the roller, thus requiring complicated work for replacement of the roller.